This invention relates to displays subject to visual anomalies resulting from differences in the time required to increase and decrease light output for individual pixel positions and, more particularly, to compensation for such anomalies in operation of liquid crystal and other displays.
A liquid crystal display (LCD) in a flat display format capable of displaying monochromatic, partial color, or full color images can be utilized in a variety of applications. Cathode ray tube (CRT) type displays provide images with pixel luminance responses capable of tracking rapid frame-to-frame changes in signal intensity of a video signal. However, that is typically not true for an LCD. Depending on the specifics of particular LCD constructions, configurations and excitation conditions, the luminance response of an LCD may be characterized by a disparity between luminance rise time, as compared to luminance decay time. Thus, there are typically measurably different time durations for switching an LCD pixel from a high intensity light output condition to a low intensity output condition, as compared to switching from low to high light output. The LCD faster video turn-off time, relative to turn-on time, results in the appearance of an “off flash” in many instances when an image is updated or moved on the display, or both moved and updated. This anomaly, which can both distract the viewer and make observation of displayed effects or data more difficult, may also be referred to as a blink anomaly. The effect may be more or less pronounced or distracting depending upon the particular type of image displayed, data content, ambient light, particular LCD construction, equipment set up, operating environment, etc., as well as differences and variations in perception and visual response of a particular viewer and from viewer to viewer.
Subsequent to their invention, the present inventors became aware of the existence of European Patent Application No. 0951007. This application discusses LCD luminance rise and decay differences and describes an approach applying complex equations to slow down a faster response over consecutive correction periods to match rising luminance to the reverse of a curve representing decaying luminance. This prior approach also provides for use of input data representing current temperature and pixel location, in attempting to determine appropriate rise/decay compensation action automatically, without operator participation. As such, this prior approach is seen as inadequate to be fully responsive to anomalies actually experienced by a particular viewer under varying operating conditions, as well as to visual response and actual perception of a viewer.
Objects of the present invention are, therefore, to provide new and improved stepped-decay video morphing methods and such methods having one or more of the following characteristics and capabilities:                customized morphing characteristics selectable by an operator while viewing screen anomalies under current actual operating conditions;        operator-optimized stepped-decay of signal intensity from a prior image to a new image;        stepped-decay video morphing with operator-adjustable interim intensity steps between old and new pixel intensities;        stepped-decay video morphing with operator selection of step magnitude and number of steps while viewing resulting display;        stepped-decay video morphing with fixed magnitude default step size in absence of operator selection; and        stepped-decay video morphing with fixed number of fixed magnitude default steps in absence of operator selection.        